1. Field of the Invention
The present invention relates to a winder of a synthetic yarn, a winding method, and cheese-like yarn package formed by the winder. More particularly, the present invention relates to a winder and a winding method capable of winding synthetic yarn at a high speed in a spinning process of synthetic yarn, and to a cheese yarn package having an excellent winding shape and a good yarn quality.
2. Description of the Related Art
A number of reports regarding high-speed production of synthetic yarns have been published during the past 10 and several years. Of special interest are the technique for manufacturing directly a yarn having practical physical properties by winding continuously a melt spun yarn into a yarn package and the technique of winding the yarn at a speed of at least 4,000 m/min, and sometimes from 8,000 m/min to 9,000 m/min. Such high-speed manufacture of synthetic yarn takes two systems: the so-called "spin take-up" process, in which the melt spun yarn is directly wound as a fully oriented yarn onto the yarn package without a drawing process, and the so-called "spin draw take-up" process, in which the melt spun yarn is wound onto the yarn package after a drawing process.
As described in U.S. Pat. Nos. 4,195,051, 4,156,071, 4,415,726, 4,426,516, and Japanese Unexamined Patent Publication (Kokai) No. 58-208416, the spin take-up process enables manufacture of a yarn dyeable under normal pressure, which is impossible with a conventional polyester yarn, by spinning the yarn at a speed of 7,000 m/min or more and winding it onto the yarn package.
The spin draw take-up process enables obtaining synthetic yarn with mechanical properties similar to those of conventional synthetic yarn by means of a high-speed winding process and is disclosed in U.S. Pat. Nos. 4,390,685 and 4,456,575.
In high-speed manufacture of synthetic yarn the high-speed causes several problems in the winding operation, e.g., inferior shape of the yarn package and irregularity of yarn quality along the lengthwise direction of the yarn as disclosed in "Journal of The Society of Fiber Science and Technology", Japan, vol. 38, No. 11. Solutions of the above problems are now under study.
When winding yarn onto a yarn package having a cheese-form, the yarn is traversed by a traverse device and wound through a contacting roll on a bobbin mounted on a bobbin shaft. Since the traversed yarn is reversed at a decreased speed at both ends of the yarn package, as is well known, a yarn dwell, i.e., yarn accumulation, is generated on the ends of the yarn package, so that the package protrudes outward at edges of end portions of the yarn package (hereinafter, referred to as "high-edge"). The diameter of the yarn package at the high-edge portions becomes slightly larger than at the middle portion. Also, the winding hardness at the high-edge portions becomes higher than at the middle portion. Therefore, during the winding operation, the yarn package is wound with only the high-edge portions pressed on the rotating contacting roll.
As driving systems for winding the yarn package, several systems may be mentioned, i.e., (1) a surface driving system, in which the contacting roll is driven, (2) a bobbin shaft driving system, in which the bobbin shaft is driven, and (3) a driving system, in which the contacting roll and the bobbin shaft are driven under cooperative control. In the above-mentioned systems (1) and (2), contact pressure is applied between the contacting roll and the yarn package, and a following member in the contacting roll or the yarn package is driven frictionally by the driving member. The contact pressure is determined as the force necessary to transmit a rotary motion to the following member without slippage and to maintain the yarn path of the yarn to be wound onto the yarn package. It is necessary to have a large contact pressure, especially for high-speed winding. This large contact pressure crushes the high-edge portions of the yarn package, resulting in bulges on the two end faces, so that the shape of the yarn package becomes inferior. Further the large contact pressure results in irregularities in the yarn quality, and irregularities in the corresponding period of the yarn between the two faces of the yarn package caused by the difference of internal stresses of the yarn prevailing in the yarn package. Further, in high-speed winding, slippage between the contacting roll and the yarn package and variation of the winding speed occur easily, further exacerbating the irregularities. When a dyeing-finishing process is applied to woven or knitted fabric fabricated from yarns of the yarn packages having the above-mentioned irregularities, the result is a flaw so-called "hikes," i.e. irregularities of brilliance caused by the weft or warp yarn running in the direction of the yarn on the woven or knitted fabric. Fabric having many "hikes" substantially lose value as merchandise. It is therefore important to eliminate "hikes" from the fabric.
There are several proposals in the related art to overcome the above-mentioned problems in the yarn package. For example, Japanese Examined Patent Publication (Kokoku) No. 49-6495 discloses a traverse cam having a specific track which is capable of decreasing the height of the high-edge portions. Japanese Examined Patent Publication (Kokoku) No. 50-22130 and Japanese Unexamined Patent Publication (Kokai) No. 60-167855 disclose a specific multi-track cam capable of traversing the yarn to disperse the high-edge portions. Japanese Unexamined Patent Publication (Kokai) No. 56-127558 discloses a scroll cam type traverse mechanism having a specific track capable of increasing the contacting area between the contacting roll and the yarn package. Japanese Unexamined Patent Publication (Kokai) No. 50-83544 discloses a method of gradually decreasing the contact pressure between the contacting roll and the yarn package.
However, when yarn is wound at a speed of 5,000 m/min or more by a conventional winder in which the above-mentioned traverse mechanism is adopted, and the yarn package is frictionally driven by a driven bobbin shaft, the yarn package sometimes collapses during the winding operation and so normal winding is difficult. Therefore the quality of the yarn package cannot be improved and it is sometimes impossible to form the yarn package.
U.S. Pat. No. 4,069,985 and 3,288,383 disclose a system in which the speed of a bobbin shaft driving means is controlled to achieve a constant winding speed by detecting the change of the power consumption of a contacting roll driving means. However, the power consumption changes by the heat generation of the contacting roll driving means, the change of the sliding resistance of bearings of the contacting roll driving means, and the like, so the above power consumption detection method is not able to keep the winding speed exactly the same, especially in the case of high-speed winding of 5,000 m/min or more.
Japanese Unexamined Patent Publication (Kokai) No. 60-209013 discloses a method for winding yarn in a noncontacting state between the yarn package and another member into a pirn-like yarn package by using a spindle driven winder. This related art suggests that improvement of the irregularities of yarn quality i.e., irregularities of "hike" and uneven dyeing, cannot be obtained by a winder having a contacting roll in which the yarn is traversed at a high speed.
Accordingly, a cheese package of synthetic yarn wound at a speed of 5,000 m/min or more having excellent shape stability and suffering from little "hike" defects when the yarn of the cheese package is directly used to manufacture a weaving fabric or a knitting fabric has not been found up to now.